AUSTIN — Front-runner David Dewhurst and tea party darling Ted Cruz were headed for another round in the Republican U.S. Senate race after Dewhurst fell shy of a majority vote Tuesday night.

Cruz, the former state solicitor general, hung close enough to Dewhurst to earn a spot in the July 31 runoff after seven other Republicans splintered the remainder of the vote.

Former Dallas Mayor Tom Leppert was running a disappointing third, while former ESPN broadcaster Craig James of Celina was far back in fourth place.

Dewhurst, in his remarks to supporters in Houston on Tuesday night, took a shot at conservative groups based in Washington that have supported Cruz.

“This evening we’ve seen a clear message from the voters to the Washington insiders, special interests — don’t mess with Texas,” he said. “Texans want to elect their own U.S. senator.”

The three-term lieutenant governor urged voters to have him replicate state government’s pro-business policies and conservative fiscal approach in Washington.

“If you like Texas, you’re going to love the job I do for you in Washington,” he said.

But Cruz said the fact that he forced a runoff “is a victory for accountability.” He lashed out at Dewhurst for skipping dozens of candidate forums and challenged the front-runner to a series of five debates by July 31.

“If he wants to make the case … that he thinks I’m an amnesty-supporting, China-loving pinko liberal, then I encourage him to do so — in person,” Cruz said, setting off whoops of delight from supporters in Houston.

In scarlet-red Texas, the Republican who emerges is all but certain to succeed U.S. Sen. Kay Bailey Hutchison, who is retiring after two decades in office.

On the Democratic side, former state Rep. Paul Sadler of Henderson was headed to a runoff against Grady Yarbrough, a retired educator from San Antonio.

No Democrat has won statewide in Texas since 1994, and though Sadler was a major player in writing state tax and school policy in those years, he has been out of office for a decade. For his Senate bid, he’s raised only about $93,000, with $5,000 of it from his own pocket — amounts he has admitted are pitiful, given the high cost of a statewide race. On Tuesday night, Sadler urged news media to demand summertime debates that include the four runoff candidates in both parties.

Sizing up the runoff

Though Dewhurst led by double digits Tuesday, experts believe he could face trouble in a runoff against Cruz. Turnout in the late summer would be even lower, and Dewhurst’s opposition wouldn’t be divided among several candidates.

And the race could draw national attention as a party-purification struggle. While Gov. Rick Perry appealed Tuesday night for voters to “send a proven conservative leader like David Dewhurst to Washington,” conservative groups outside Texas were quick to claim credit for Cruz making the runoff and said they’d spend even more to help him.

Chris Chocola, president of Club for Growth, noted that the anti-tax group already has spent $2.5 million on anti-Dewhurst ads.

Rice University political scientist Mark Jones said depressed turnout could be a boon for Cruz, whose supporters “are in most instances more enthusiastic and more motivated to vote on the 31st.”

But he said Dewhurst will try mightily to persuade his backers to return to the polls, and to woo people who voted for Leppert.

Jones noted that Dewhurst, who spent more than $20 million of personal funds to get elected lieutenant governor in 2002, has spent $10 million from his own pocket this time.

“Since money’s not really an object, he’ll be able to — between direct mail and calls — really get people out and try to motivate them,” Jones said. “And he’ll be able to continue to hammer on Cruz with the negative.”

Big spending

The GOP Senate battle drew more than $30 million of spending by the nine candidates and independent groups.

The tone was nasty, as the pro-Dewhurst and pro-Cruz forces traded accusations about the lieutenant governor’s fiscal record and Cruz’s work on behalf of a Chinese company battling an American tire inventor over intellectual-property claims.

Dewhurst, trying to shave a few percentage points off his two main rivals, launched last-minute ads accusing Cruz of supporting amnesty for illegal immigrants and saying Leppert is a liberal who “governs as a Democrat.”

Cruz, calling the Dewhurst claims “bald-faced lies,” said he opposes creating a new legal path to citizenship for people in this country illegally. Leppert said he was a conservative manager at Dallas City Hall. His spokesman called Dewhurst “a career politician who is willing to lie in order to win at any cost.”

As the top three — Dewhurst, Cruz and Leppert — poured millions into ads, it became clear that first-time candidate James, the former SMU star running back, jumped into the race too late and was unable to build a financial war chest to compete.

James said Tuesday that while he accepts the voters’ decision, he intends “to stay actively involved in the conservative movement, and to have my voice heard.”

Leppert, who called the results disappointing, declined to say if he will endorse a candidate in the runoff or whom that might be.

“I felt like we conducted the campaign in the right manner, and I felt like we conducted ourselves in ways we can be proud of,” he said.